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Proceeding with TKA without preoperative anticoagulation for asymptomatic calf vein thrombosis shows no 90-day VTE eventsSkip the delay for a minor clot before knee surgery

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Key Takeaway
Consider observational data suggesting proceeding with TKA without preoperative anticoagulation for asymptomatic calf DVT may be safe under protocolized care.

This retrospective cohort study analyzed 454 consecutive adults undergoing primary unilateral total knee arthroplasty (TKA) from 2019 to 2023. The study compared 44 patients with preoperative screen-detected, asymptomatic isolated muscular calf vein thrombosis (MCVT) to 410 controls without thrombosis. All patients proceeded with TKA as scheduled without preoperative therapeutic-dose anticoagulation, following a standardized enhanced recovery after surgery (ERAS) pathway that included combined mechanical prophylaxis and standard chemoprophylaxis (enoxaparin or rivaroxaban).

Within the 90-day follow-up period, no symptomatic venous thromboembolism or pulmonary embolism occurred in either group (0/44 vs. 0/410; 95% CI 0.0%–8.0% and 0.0%–0.9%). Routine duplex ultrasonography on postoperative day 5 showed no thrombus progression or new deep vein thrombosis. No ISTH-defined major bleeding or clinically relevant non-major bleeding events were reported. Knee Society Scores and length of stay were similar between groups (all P > 0.05).

The study has several limitations, including its retrospective, single-center design and descriptive nature. The findings are hypothesis-generating and cannot exclude rare but clinically important differences in outcomes. The absence of reported funding or conflict of interest details is a limitation. For clinical practice, these observational data suggest that, within a protocolized ERAS pathway, proceeding with TKA without delay or preoperative therapeutic anticoagulation in patients with asymptomatic isolated MCVT may be associated with no clinically evident thrombotic or bleeding events at 90 days. However, prospective multicenter studies are needed to quantify rare event risks and clarify generalizability.

  • Small clots in calf muscles don't stop knee surgery or cause blood clots in the lungs.
  • Patients can proceed with standard care and no extra blood thinners before the operation.
  • This approach avoids unnecessary delays and keeps recovery on track for most people.

Finding a clot shouldn't stop your surgery

Imagine you are scheduled for a major knee replacement. You are excited about getting back to walking without pain. Then, a quick ultrasound scan shows a small clot in your calf muscle. You might think this means you must wait weeks for the clot to go away. You might also worry that you need stronger blood thinners before the operation.

But new research suggests you can skip the wait.

Deep vein thrombosis is a serious risk for people having joint replacements. Doctors usually scan patients before surgery to check for clots. If a clot is found, the standard rule has been to delay surgery and start strong blood thinners.

This rule protects patients from dangerous blood clots traveling to the lungs. However, it also delays surgery and increases bleeding risks. Many patients have small clots in their calf muscles that never cause problems. These are called isolated muscular calf vein thrombosis.

Doctors have not had enough data on these specific small clots. They often treated them like big, dangerous clots. This led to unnecessary delays and extra risks for patients who did not need them.

The surprising shift

This study looked at patients getting knee replacements from 2019 to 2023. Researchers scanned 454 patients with ultrasounds five days before surgery. About 10% of them had these small, silent clots in their calf muscles.

The team did not delay surgery for anyone with these small clots. They also did not give extra blood thinners before the operation. Instead, they used a standard plan. This plan included a blood thinner after discharge and early walking after surgery.

What scientists didn't expect

The results were clear. None of the patients with small clots had a dangerous blood clot in their lungs. None of them had a new, big clot form after surgery. The small clots did not grow or move up the leg.

Patients with small clots did just as well as those without them. Their knee scores were the same. Their hospital stays were the same. There was no extra bleeding in either group.

The lock and key analogy

Think of your blood vessels like a busy highway. A small clot in a tiny side road is like a parked car in a driveway. It does not block traffic on the main highway.

The main highway is the deep vein system near the heart and lungs. That is where dangerous clots live. The small clots in the calf muscles are in tiny side roads. They are far from the main highway.

Current treatments often treat the driveway like the highway. They use heavy traffic control (strong blood thinners) for a parked car. This study shows you do not need heavy traffic control for a parked car in the driveway.

The study included 454 adults getting their first knee replacement. All patients got a standard scan before surgery. Those with small clots went straight to surgery. Everyone got a standard blood thinner plan after leaving the hospital. They also used compression stockings and walked early.

The most important finding is safety. Zero patients in the small clot group had a dangerous blood clot. This is the same result as the group with no clots at all.

The study also checked for bleeding. No one had major bleeding. No one had bleeding that needed medical attention. The small clots did not cause harm.

This doesn't mean this treatment is available yet.

Doctors say these findings are promising but need more proof. This was a single hospital study. It shows a pattern, but larger studies are needed. The goal is to confirm that this works for everyone.

If you have a small clot found before surgery, do not panic. Talk to your surgeon about the size and location of the clot. If it is small and in the calf muscle, you might not need to wait.

Always follow your doctor's advice. They know your full medical history. They will decide if you need to wait or if you can proceed with standard care.

This study was done at one hospital. It looked at a specific type of clot. It cannot prove that this works for every patient everywhere. Rare events might still happen. More research is needed to be sure.

Researchers will now look at more hospitals. They want to see if this works for different types of clots. They also want to study patients with other risk factors. This will help doctors make better decisions for everyone.

Would you consider this if it becomes available?

Study Details

Study typeCohort
EvidenceLevel 3
PublishedApr 2026
View Original Abstract ↓
BackgroundLimited evidence exists regarding the management of preoperative screen-detected (by duplex ultrasonography) asymptomatic isolated muscular calf vein thrombosis (MCVT) before total knee arthroplasty (TKA). We evaluated the outcomes when TKA was performed as scheduled, without preoperative therapeutic-dose anticoagulation, using a standardized thromboprophylaxis and enhanced recovery after surgery (ERAS) pathway.MethodsConsecutive adults undergoing primary unilateral TKA from 2019 to 2023 received bilateral duplex ultrasonography within 5 days before surgery. The MCVT group comprised patients with asymptomatic isolated gastrocnemius or soleal vein thrombosis, with no involvement of axial deep calf veins or the popliteal vein; the control group had no thrombosis. All patients received a standardized pharmacological prophylaxis regimen (enoxaparin in-hospital followed by rivaroxaban after discharge, total duration 14 days), along with mechanical prophylaxis and early mobilization. The primary outcome was symptomatic venous thromboembolism (VTE) within 90 days. Secondary outcomes included duplex ultrasonography findings on postoperative day 5, bleeding events [defined by International Society on Thrombosis and Hemostasis (ISTH) criteria], Knee Society Score (KSS) at 90 days, and length of stay.ResultsAmong 454 patients included, 44 (9.7%) had an isolated preoperative MCVT. No patients in either group developed symptomatic VTE or pulmonary embolism (0/44 vs. 0/410, 95% CI 0.0%–8.0% and 0.0%–0.9%). Routine duplex ultrasonography on postoperative day 5 showed no thrombus progression or new deep vein thrombosis (DVT) in either group. No ISTH-defined major bleeding or clinically relevant non-major bleeding (CRNMB) occurred. KSS outcomes and length of stay were similar between groups (all P > 0.05).ConclusionUnder a protocolized ERAS pathway with combined mechanical prophylaxis and standard chemoprophylaxis, we observed no clinically evident thrombotic or bleeding events within 90 days in patients with asymptomatic isolated preoperative MCVT who proceeded to TKA without delay or preoperative therapeutic-dose anticoagulation. These findings are descriptive and hypothesis-generating and cannot exclude rare but clinically important differences; prospective multicenter studies are needed to quantify rare events and clarify generalizability across thrombus profiles and prophylaxis regimens.
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